The EJB Container
The Java EE specification introduces the concept of the Enterprise JavaBeans (EJB) container for the express purposes of running business logic in the form of session beans, data access logic in the form of entity beans, and message handling logic in the form of message-driven beans. The typical behavior envisioned by the Java EE specification is that a developer writes an Enterprise JavaBean, a simple component, and the EJB container adds the necessary infrastructure for communications, transactions, and data access to turn that business logic into something that executes. In addition, the EJB container provides the lifecycle management for the component to ensure that its creation, usage, and destruction are both efficient and in accord with the specification. To do this, the underlying infrastructure is expected to build on the functionality of a CORBA ORB for the security and interoperability, but this still leaves a large gap in the required infrastructure that is left for an application server vendor to develop. For WebSphere Application Server, the additional infrastructure built on the ORB to support the EJB specification is provided by the Enterprise Java Services (EJS) container layer that underpins the EJB container itself.
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